| 摘要 |
Compounds of the formula <IMAGE> I wherein R1 signifies trans-4-alkylcyclohexyl, 4'-alkyl-4-biphenylyl, p-(trans-4-alkylcyclohexyl)phenyl, 2-(trans-4-alkylcyclohexyl)ethyl or p-[2-(trans-4-alkylcyclohexyl)ethyl]phenyl and R2 signifies trans-4-alkylcyclohexyl; or R1 signifies trans-4-alkylcyclohexyl and R2 signifies p-(trans-4-alkylcyclohexyl)phenyl, p-[2-(trans-4-alkylcyclohexyl)ethyl]phenyl or 4'-(trans-4-alkylcyclohexyl)-4-biphenylyl; or R1 signifies p-alkylphenyl and R2 signifies p-[2-(trans-4-alkylcyclohexyl)ethyl]phenyl, and the alkyl groups in the substituents R1 and R2 are straight-chain groups containing 1 to 7 carbon atoms, liquid crystalline mixtures which contain these compounds and their use for electro-optical purposes are described. The novel compounds of formula I are especially valuable as components in liquid crystal mixtures and themselves have liquid crystalline properties.
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